Brig. Gen. Jeffrey Sinclair leaves the courthouse following a day of motions, Tuesday, at Fort Bragg, N.C. Less than a month before Sinclair’s trial on sexual assault charges, the lead prosecutor broke down in tears Tuesday as he told a superior he believed the primary accuser in the case had lied under oath.

FORT BRAGG, N.C. — In his immaculate blue dress uniform, Brig. Gen. Jeffrey A. Sinclair stood ramrod straight before a judge Thursday and pleaded guilty to three charges that could send him to prison for up to 15 years.

It was a remarkable admission sure to end the military career of a man once regarded as a rising star among the U.S. Army’s small cadre of trusted battle commanders.

Sinclair, 51, still faces five other charges stemming from the claims of a female captain nearly 20 years his junior who says the general twice forced her to perform oral sex. But by pleading guilty to the lesser charges, Sinclair’s lawyers believe they will strengthen his case at trial by potentially limiting some of the salacious evidence prosecutors can present.

The former deputy commander of the 82nd Airborne could be sentenced to life in prison if convicted of the sexual assaults. Opening statements were expected Friday.

Asked by judge Col. James Pohl whether he clearly understood the consequences of his admissions, the decorated veteran of five combat deployments answered in a clear voice, with no emotion: “Yes sir.”

Pohl accepted Sinclair’s plea after nearly three hours of often intimate questions about the married general’s flirtations and dalliances with four women — three military officers and one civilian.

Repeatedly, Sinclair turned to his lawyer before answering, prompting the judge to say: “It’s important that you tell me the truth as you recall it.”

“You’ll get nothing but the truth from me,” the general replied.

The case against Sinclair, believed to be the most senior member of the U.S. military ever to face trial on sexual assault charges, comes as the Pentagon grapples with revelations of rampant rape and sexual misconduct within the ranks. The U.S. Senate on Thursday blocked a bill that would have stripped senior military commanders of their authority to prosecute rapes and other serious offenses in the ranks. The bill was firmly opposed by the Pentagon.

The general pleaded guilty to having improper relationships with two female Army officers and to committing adultery with a third, the captain who was his longtime mistress. Adultery is a crime in the military.

When asked by the judge if he was aware of the prohibition against senior officers having relations with subordinates, Sinclair replied, “Oh, yes sir.”

He then described how the affair began during a war tour in Iraq when his primary accuser asked if he wanted to watch a movie. Once they were alone in his quarters, the general said the young officer made sexual advances that he initially rebuffed.

Pohl asked how Sinclair knew the woman wanted to have sex with him.

“Probably when she took her top off, sir,” the general said with a nervous chuckle.

Sinclair’s wife of nearly 30 years has remained with him through his legal troubles and served as a staunch public defender, though she was not in the courtroom Thursday as he admitted guilt. The couple has two children.

The general also admitted to violating orders by possessing pornography and to conduct unbecoming an officer and a gentleman. After he knew he was under investigation, Sinclair also admitted deleting nude photos from a personal email account sent by a civilian woman with whom he was childhood friends.